1261865842 has 4 divisors (see below), whose sum is σ = 1892798766. Its totient is φ = 630932920.

The previous prime is 1261865837. The next prime is 1261865879. The reversal of 1261865842 is 2485681621.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 1153892961 + 107972881 = 33969^2 + 10391^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 315466459 + ... + 315466462.

Almost surely, 2^1261865842 is an apocalyptic number.

1261865842 is a deficient number, since it is larger than the sum of its proper divisors (630932924).

1261865842 is an equidigital number, since it uses as much as digits as its factorization.

1261865842 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 630932923.

The product of its digits is 184320, while the sum is 43.

The square root of 1261865842 is about 35522.7510477440. The cubic root of 1261865842 is about 1080.6151736471.

The spelling of 1261865842 in words is "one billion, two hundred sixty-one million, eight hundred sixty-five thousand, eight hundred forty-two".